急，DataGrid的TableStyle中MappingName不设置他就不显示

[CalvinDotNet]

谢谢各位高手，
如下dataGridTextBoxColumn3就显示，dataGridTextBoxColumn4就不显示
就因为dataGridTextBoxColumn4的MappingName=""，
dataGridTextBoxColumn4是要给用户自己填的数量，不映射到数据库的，怎么办呢

//
// dataGridTextBoxColumn3
//
this.dataGridTextBoxColumn3.Format = "";
this.dataGridTextBoxColumn3.FormatInfo = null;
this.dataGridTextBoxColumn3.HeaderText = "中文名称";
this.dataGridTextBoxColumn3.MappingName = "ChineseName";
this.dataGridTextBoxColumn3.Width = 75;
//
// dataGridTextBoxColumn4
//
this.dataGridTextBoxColumn4.Format = "";
this.dataGridTextBoxColumn4.FormatInfo = null;
this.dataGridTextBoxColumn4.HeaderText = "数量";
this.dataGridTextBoxColumn4.MappingName = "";
this.dataGridTextBoxColumn4.Width = 75;